/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.extensions.sql.meta.store;



import com.bff.gaia.unified.sdk.extensions.sql.UnifiedSqlTable;

import com.bff.gaia.unified.sdk.extensions.sql.meta.Table;

import com.bff.gaia.unified.sdk.extensions.sql.meta.provider.TableProvider;

import com.bff.gaia.unified.vendor.guava.com.google.common.collect.ImmutableMap;

import com.bff.gaia.unified.sdk.extensions.sql.UnifiedSqlCli;



import java.util.HashMap;

import java.util.Map;



/**

 * A {@link MetaStore} which stores the meta info in memory.

 *

 * <p>NOTE, because this implementation is memory based, the metadata is NOT persistent. for tables

 * which created, you need to create again every time you launch the {@link

 * UnifiedSqlCli}.

 */

public class InMemoryMetaStore implements MetaStore {

  private Map<String, Table> tables = new HashMap<>();

  private Map<String, TableProvider> providers = new HashMap<>();



  @Override

  public String getTableType() {

    return "store";

  }



  @Override

  public void createTable(Table table) {

    validateTableType(table);



    // first assert the table name is unique

    if (tables.containsKey(table.getName())) {

      throw new IllegalArgumentException("Duplicate table name: " + table.getName());

    }



    // invoke the provider's create

    providers.get(table.getType()).createTable(table);



    // store to the global metastore

    tables.put(table.getName(), table);

  }



  @Override

  public void dropTable(String tableName) {

    if (!tables.containsKey(tableName)) {

      throw new IllegalArgumentException("No such table: " + tableName);

    }



    Table table = tables.get(tableName);

    providers.get(table.getType()).dropTable(tableName);

    tables.remove(tableName);

  }



  @Override

  public Map<String, Table> getTables() {

    return ImmutableMap.copyOf(tables);

  }



  @Override

  public UnifiedSqlTable buildUnifiedSqlTable(Table table) {

    TableProvider provider = providers.get(table.getType());



    return provider.buildUnifiedSqlTable(table);

  }



  private void validateTableType(Table table) {

    if (!providers.containsKey(table.getType())) {

      throw new IllegalArgumentException("Table type: " + table.getType() + " not supported!");

    }

  }



  @Override

  public void registerProvider(TableProvider provider) {

    if (providers.containsKey(provider.getTableType())) {

      throw new IllegalArgumentException(

          "Provider is already registered for table type: " + provider.getTableType());

    }



    initTablesFromProvider(provider);

    this.providers.put(provider.getTableType(), provider);

  }



  private void initTablesFromProvider(TableProvider provider) {

    Map<String, Table> tables = provider.getTables();

    for (String tableName : tables.keySet()) {

      if (this.tables.containsKey(tableName)) {

        throw new IllegalStateException(

            "Duplicate table: " + tableName + " from provider: " + provider);

      }

    }

    this.tables.putAll(tables);

  }



  Map<String, TableProvider> getProviders() {

    return providers;

  }

}